JPH028779A - Human body detector - Google Patents

Abstract

PURPOSE:To prevent that the title detector is affected by the irregularity in the sensitivity of an infrared detection element by setting the magnitude of a threshold value for detecting the rising time of the infrared detection element from the output thereof according to the magnitude of a peak value when the title apparatus is constituted by the use of a plurality of the infrared detection elements. CONSTITUTION:There is irregularity in the respective sensitivities of infrared detection elements A to D and, even when infrared rays of the same intensity are inputted, the peak values of the outputs of said element become irregular and, therefore, when a threshold value for determining the rising time of a signal is generated in the time at the time of judgement. By this method, even when there is irregularity not only in the sensitivities of the elements but also in the peak values of the outputs of said elements, no irregularity is generated in output times. Therefore, the peak values of the respective outputs of the elements A to D, the threshold value and the output times are judged by a judging part 5 wherein the outputs of the infrared detection elements A to D composed of four pyroelectric elements are provided in a post stage and the threshold value is changed to determine threshold values of every elements and these values are mutually compared to judge the presence of a human body.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is an infrared receiving type that detects the difference between the amount of infrared rays emitted from the human body and the amount of infrared rays emitted from the background such as the floor surface by the movement of the human body. The present invention relates to a human body detection device.

[Conventional technology]

An infrared receiving type human body detection device is a device that detects a human body by detecting the temperature difference between the human body and the background as a difference in the amount of infrared energy using an infrared detection element such as a pyroelectric element, and has become widely popular in recent years. However, along with this, improvements in reliability are required. Possible causes of malfunction of infrared-receiving human body detection devices include background temperature changes within the detection area, internal noise, and the influence of high-energy disturbance light such as headlights and sunlight. Various proposals have been made in the past to remove this.

As one example, as shown in FIG. 6, infrared rays from a detection area are collected by a light receiving system 1, and the collected infrared rays are transmitted to an infrared detecting element section 2 consisting of a plurality of infrared detecting elements A to D.
, each output is independently amplified by the amplifier 3, and then subjected to signal processing by the signal processing unit 4, and includes a threshold setting unit 51 and a comparison/judgment unit 52 for setting a certain threshold. The determination unit 5 detects the peak value and the output time, compares these with each other to determine the presence or absence of a human body, and outputs this determination result from the output unit 6, which is reliable and does not depend on the direction of movement of the human body. A highly sensitive human body detection device has been proposed (Japanese Patent Application No. 62-242090).

[Problem to be solved by the invention]

However, this human body detection device has the problem that if there are variations in the sensitivity of each infrared detection element, differences will occur in the output peak value and output rise time, which will affect the judgment of human body detection. there were.

The present invention has been made in view of the above points, and its purpose is to provide a human body detection device using a plurality of infrared detection elements with reliability that is not affected by variations in sensitivity of each infrared detection element. The objective is to provide a highly sophisticated human body detection device.

[Means to solve the problem]

The present invention includes an optical system that collects infrared rays from a detection area;
a plurality of infrared detection elements that receive infrared light focused by the optical system; an amplification section that amplifies each output of the plurality of infrared detection elements; and each of the infrared detection elements amplified by the amplification section. A signal processing unit processes the output into a signal suitable for human body detection, and a peak value and output time are detected from each output of the infrared detection element processed by the signal processing unit, and these are compared with each other to determine the presence or absence of a human body. A human body detection device comprising: a determination section for determining a determination result; and an output section for outputting a determination result of the determination section, wherein a threshold value for determining an output time in the determination section corresponds to the peak value. This feature is characterized in that the settings can be made as follows.

[Operation] In the human body detection device of the present invention, the threshold value for detecting the rise time from each output of the plurality of infrared detection elements is variable depending on the magnitude of the peak value of the output of each infrared detection element. In other words, by setting the threshold value for each infrared detection element by increasing the threshold value when the peak value is large and decreasing the threshold value when the peak value is small, the output of each infrared detection element can be adjusted. By setting the time required for rise to be constant, the influence of variations in sensitivity among a plurality of infrared detection elements is attempted to be reduced.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. Although this embodiment shows a case in which there are four infrared detecting elements, the present invention can also be applied to a case in which a number of infrared detecting elements other than four is used.

l is an optical system that uses a mirror or lens to collect infrared rays from a detection area. In this embodiment, a multi-segmented mirror or multi-segmented lens is used to collect infrared rays from multiple detection areas. . Reference numeral 2 denotes an infrared detection element section, in which infrared detection elements A to D consisting of four pyroelectric elements or the like are arranged on the focal plane of the optical system 1. Reference numeral 3 denotes an amplifying section that independently amplifies the outputs of the infrared detecting elements A to D. 4 is a signal processing unit, which is provided with a bandpass filter and extracts only the necessary frequency components from each output, and each output that has passed the bandpass filter is sequentially A/D-digitized using a multiplexer and an A/D converter.
converted.

Reference numeral 5 denotes a judgment section, which includes a threshold value setting section 51 and a comparison/judgment section 52.
Peak values VA~VD and threshold values VTA~VT from each output of D
D and output times tA to t, D are detected and compared with each other to determine the presence or absence of a human body.

The threshold value setting unit 51 uses each peak value ■^~VD from each output of the infrared detection elements A-D processed by the signal processing unit 4 to determine threshold values VT^~VTD based on the magnitude thereof. In other words, in general, infrared detection elements A-D have different sensitivities, and even if infrared rays of the same intensity are input, the output peak values VA-VD will vary, so the second
As shown in the figure, if the threshold value for determining the signal rise time is set to a - constant value VT, the time required for the rise from the signal input start point 10 to the time tA to tD, which is determined to be the signal rise time, is TA-TD. Variations will occur. In the example of FIG. 3(a), different peak values V
The rise times for P1 and VF6 are different as t and L2, respectively. However, in this type of human body detection device that detects a human body using a plurality of infrared detection elements A to D, human body detection is determined based on the correlation between output times (signal rise times) tA to tD. , it is necessary to eliminate variations in output times LA-LD between elements. Therefore, in this example, the sensitivity of the infrared detection elements A to D varies, and the peak (
Even if the direct lines VA to VD vary, the output time LA-tD is prevented from varying. In the example of FIG. 3(b), each threshold value is set to VTI for different peak values VPI and VF6.

It is set to a different value from VT2. That is, by setting a large threshold value for a large peak value and a small threshold value for a small peak value, the rise time can be made constant such as time t. Therefore, as shown in Fig. 4, in the case of large peak values such as peak values VA and VC, the threshold values VT^ and VTC are also increased accordingly, and in the case of small peak values such as peak values VB and VD, the threshold values VT^ and VTC are also increased accordingly. In the case of a value, the threshold value VTR1VTD is also made small according to the value, so that the time T from the signal input start point to to the signal rise time LA-tD is kept constant. Specifically, for example, assuming that the rise of the signal is linear, the threshold value VTA-VTD may be calculated from each peak value ~VD based on the following equation.

(Peak value Vi)/(Threshold value VTi) Constant number, provided that i
;^, B, C, D 6 is an output section which outputs the judgment result from the judgment section 5.

Next, the operation of this embodiment will be explained. By arranging a plurality of infrared detection elements A-D on the focal plane of the optical system 1,
A plurality of detection areas are formed on the object plane through the optical system 1 in the same arrangement as the infrared detection elements A to D on the focal plane, and as the human body moves within the detection area, each of the infrared detection elements A to D produces an output as a change in temperature difference from the background. The output from the infrared detecting elements A-D is sent to the amplifier section 3.
The signal is amplified by the signal processing section 4, processed into a signal suitable for human body detection, and inputted to the judgment section 5.

In the threshold value setting section 51 in the judgment section 5, each infrared detection element A
Using the peak value VA-VD from -D, each peak value V
A threshold value VTD is determined such that the time T from the signal input start point LO to the signal rise time tA-LD remains constant even if the magnitude of A-VD varies. In the comparison/judgment section 52, the output times LA-LD from each infrared detection element A-D are determined using the threshold values VTA to VTD, and these are compared with each other to determine the output time LA-LD from each infrared detection element A-D.
The presence or absence of a human body and the direction of movement are determined based on the order in which the output from the robot rises.

In addition, a peak value storage section for each of the infrared detection elements A to D is provided in the threshold value setting section 51, and the average value of the peak values from the past to the present for each infrared detection element A to D is determined, and the value is set as the peak value. Used as values VA~■D, threshold values VTA~VT
If D is determined, the influence of variations in peak values VA to VD due to the surrounding environment such as ambient temperature can be suppressed, and the infrared detection element A
It is possible to correct the influence of variations only in -D.

Further, as shown in FIG. 5, the human body detection device is equipped with a standard heat source 7 such as a nichrome wire and an auxiliary optical system 8 for guiding infrared rays from the standard heat source 7 to each infrared detection element A to D. If the threshold values VTA to VTD of each infrared detection element A to D are determined using the infrared output from the standard heat source 7, the influence of variations in the peak values VD due to the surrounding environment such as ambient temperature can be suppressed, and the This makes it possible to correct the influence of variations in only the detection elements A to D.

〔Effect of the invention〕

As described above, according to the present invention, there is provided an optical system that collects infrared rays from a detection area, a plurality of infrared detection elements that receive the infrared rays collected by the optical system, and a plurality of infrared detection elements that receive the infrared rays collected by the optical system. an amplification section that amplifies each output, a signal processing section that processes each output of the infrared detection element amplified by the amplification section into a signal suitable for human body detection, and an infrared detection element processed by the signal processing section A human body detection device comprising: a determining unit that detects a peak value and an output time from each output, and compares these with each other to determine the presence or absence of a human body; and an output unit that outputs the determination result of the determining unit. Since the threshold value for determining the output time in the determination section is set in correspondence with the peak value, the human body detection device is highly reliable and is not affected by variations in sensitivity of each infrared detection element. could be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIGS. 2 to 4 are waveform diagrams for explaining the operation of the above, and FIG. 5 is a block diagram showing another embodiment of the present invention. Figure, 6th
The figure is a block diagram showing a conventional example. 1-1 Optical system 2-...Infrared detection element part A
-D-Infrared detection element 3-Amplification section 4-Signal processing section 5-Judgment section 52--Comparison judgment section 7--Standard heat source 51-Threshold value setting section 6-Output section 8-Auxiliary light source

Claims (1)

[Claims] (1) An optical system that collects infrared rays from a detection area, a plurality of infrared detection elements that receive the infrared rays collected by the optical system, and an amplification that amplifies each output of the plurality of infrared detection elements. a signal processing section that processes each output of the infrared detection element amplified by the amplification section into a signal suitable for human body detection, and a peak value and a peak value from each output of the infrared detection element processed by the signal processing section. A human body detection device comprising: a determination unit that detects output times and compares them with each other to determine the presence or absence of a human body; and an output unit that outputs a determination result of the determination unit, the determination unit A human body detection device characterized in that a threshold value for determining an output time in is set corresponding to the peak value.